Im just wondering what would be suitable to use as a substitute for high ratio shortening in a crusting BC? I think the only shortening I know of is copha.
There isn't an Australian equivalent for any shortening (Copha can be used for some uses eg for rolling out fondant/gumpaste etc but not in icing recipes). You can get Crisco from some US import stores, David Jones and, I kid you not, some sex shops! But that isn't the same as hi-ratio. You might be able to order from the US but that is going to cost!